1. Field of the Invention
This invention relates to silver halide photographic light-sensitive materials, and more particularly to silver halide color photographic light-sensitive materials.
2. Description of the Prior Art
The silver halide photographic light-sensitive material (hereinafter referred to occasionally as "sensitive material" for short where there exists no possibility of entailing confusion) is produced by purposively superposing various photographic layers including a silver halide emulsion layer possessing photosensitivity and other various auxiliary layers vested with auxiliary functions such as, for example, an anti-irradiation layer, an anti-halation layer, an intermediate layer for intercepting interlayer effects, a filter layer, and a protective layer. The silver halide color photographic light-sensitive layer (hereinafter referred to occasionally as "color sensitive material" for short where there exists no possibility of entailing confusion) contains a coupler which produces a color spectral zone matched under a fixed mechanism with a sensitivity spectral zone of a silver halide emulsion layer.
In the photographic layers of these sensitive materials, a hydrophilic colloid such as of gelatin is used as a binder. Recently, the photographic layers are generally subjected to a hardening treatment so as to withstand the latest rapid treatment carried out at elevated temperatures and high pH values and the mechanical treatment performed as with an automatic developer and tended to entail infliction of damages such as scratches and stubs and, at the same time, to meet the requirement put forth in the aspect of productivity.
The success of this hardening treatment is indispensable to the assurance of quality in the phase of physical properties, except for special cases. So far, various hardening agents ranging from primitive hardening agents of inorganic compounds such as potash alum and chrom alum to organic hardening agents satisfying highly advanced photographic properties have been studied for feasibility.
Examples are chlorotriazine type hardening agents disclosed in U.S. Pat. Nos. 3,325,287 and 3,645,743 and Japanese Patent Application Laid-open SHO 57(1982)-40244, vinyl sulfone type hardening agents disclosed in U.S. Pat. No. 3,490,911 and West German Pat. (OLS) No. 2,749,260, and many other hardening agents such as of aldehyde type and epoxy type.
Besides the prerequisite for possessing a hardening effect, the requirements which the hardening agent is expected to fill are that the hardening agent should confer a glossly surface upon hardening, that it should allow the layers to adhere fast to the support, that it should enable the layers to harden quickly, that it should impart high scratch resistance to the layers, that it should do no harm to photographic properties, that it should avoid jeopardizing labor hygiene, and that it should have no possibility of entailing any environmental pollution.
Regarding these requirements, the S-triazine type hardening agents lack the rapid hardening property, the vinyl sulfone type hardening agents lack the gloss and the adhering property, and other hardening agents lack some other properties, whereas the chlorotriazine type hardening agents possess properties satisfying at least the aforementioned requirements.
These chlorotriazine type hardening agents, however, are deficient photographic properties, particularly because of regression of latent image. The regression of latent image suffered by these hardening agents is particularly prominent when these hardening agents are used in combination with 2-acylaminophenol type cyan couplers possessing highly advantageous properties.
Generally, the regression of latent image occurs abruptly in the early stage immediately after exposure and then describes a gentle declining slope. The shape of the curve of latent image regression and the magnitude of latent image regression are heavily affected by pH, pAg, humidity, and other chemical factors of the photographic layers, most directly of the emulsion layer, of the sensitive material.
In the color light-sensitive material, when the color developing layer of a specific type, particularly the color developing layer containing, as a coloring matter, a cyan coupler disposed to produce a readily fading cyan dye or a cyan coupler improved to retard fading, induces greater regression of latent image than other component layers, the color balance is seriously impaired even to the extent of depriving the color image of its value.
The hardening agent to be used as one of the essential components for the photographic layers in the aforementioned sensitive material lowers the pH value of the photographic layer as the hardening reaction proceeds. Thus, the hardening reaction may well be regarded as one factor for the regression of latent image.
For the prevention of the regression of latent image and in view of the peculiar behavior of pH mentioned above, attempts are made at increasing the pH value of the photographic layer. Generally, an increase in the pH value entails aggravated fogging and degraded long-term storability. Thus, the increase of the pH value does not prove an advantageous measure for the prevention of latent image regression from the standpoint of all the properties of the sensitive material.
Measures for the prevention of latent image regression by incorporation of various stabilizers as disclosed in Japanese Patent Application Laid-open SHO 56(1981)-1043 and British Pat. Nos. 1,458,197, 1,389,089, 1,386,630, and 1,378,354 are effective as claimed. However, the addition of such stabilizers results in lowered sensitivity, degraded long-term storability, and spoiled processing liquid. Japanese Patent Application Laid-open SHO 48(1973)-3527 teaches a method of preventing the regression of latent image by having a specific sensitizing dye adsorbed on silver halide particles. This method spoils the harmony between the sensitivity spectrum required by the emulsion layer and the absorption spectrum given by the dye, and brings about contamination of the dye also impairs storability. This method is far from serving as a satisfactory measure for the prevention of latent image regression for the sake of the sensitive material, particularly the color sensitive material.